> You can always mutate things in a local context (i.e. objects that are either owned or uniquely borrowed) You do have to explicitly declare them mutable, tho

> You can always mutate things in a local context (i.e. objects that are either owned or uniquely borrowed) You do have to explicitly declare them mutable, though, and will warn you if you have a mutable variable that you never mutate. This is helpful for avoiding surprises.